1. Field of the Invention
Embodiments of the present invention relate to a printing apparatus.
2. Description of the Related Art
Conventionally, in a printing apparatus for forming an image on a web, which is a continuous strip media, for example, the following web conveyance method is known. Namely, pin components of a printer tractor mounted in the printing apparatus are engaged to sprocket holes of the web, and the web is conveyed when the printer tractor is driven. However, when the web having the sprocket holes are used, both end portions of the web having the sprocket holes may be cut after printing. Therefore, the following apparatus has been realized conventionally. Namely, in an apparatus, a web not having the sprocket holes is used. The apparatus conveys the web using a conveyance roller system instead of the printer tractor.
Further, in a field of such a printing apparatus, in order to improve productivity, a demand for faster print speed and a demand for reduction of downtime are increasing. Therefore, the following printing system is more widely used than the box-paper printing in which an operator intervenes every several thousand feet and supplies paper. Namely, a printing system includes a web feeding device located upstream of the printing system. In the printing system, a roll paper that enables continuous printing is used. Here, in the roll paper, several tens of thousands of feet of paper is wound in a roll-like shape.
Conventionally, a printing apparatus including: a control means that controls, before printing, a web conveyance position and a tension on the web on upstream side in a web conveyance direction; and a control means that controls, after printing, a web conveyance position and a tension on the web on downstream side in the web conveyance direction, is known (e.g. Patent Document 1 (Japanese Published Unexamined Publication No. 2001-335206)). Further, a web tension providing device of a printing device that includes: a tension adjusting means for adjusting a tension on a web using pressing forces from a drum and a pressing roller that pinch the web; and a suspending system to visualize whether the tension on the web is strong or weak, is known (e.g. Patent Document 2 (Japanese Published Unexamined Publication No. 2004-250203)).
Further, a printing device including: a tension adjusting guide which operates separately from a tension generating roller so as to provide a suitable tension to various types of webs including a web to which a tension is easily provided and a web to which a tension is not easily provided, is known (e.g. Patent Document 3 (Japanese Published Unexamined Publication No. 2006-248722)). Further, a sheet conveyance device that detects a width of a paper sheet and that separates a tension providing means placed in a region not facing to the paper sheet from a sheet contacting means is known (e.g. Patent Document 4 (Japanese Published Unexamined Publication No. 2009-227396)).